The video refers, quite apparent, two prototypes : the Lumia 920 with the color gray, spotted a few weeks ago, and the Lumia 820 with the white shell. A video interesting because it allows to evaluate more specifically the differences between the form-factor of the two devices .
The new top of the range Nokia Windows Phone 8 takes what made the very popular Nokia N9, the first and the Lumia 800 and 900, later. Design substantially unpublished, on the contrary, for the Lumia 820, that to the body of the unibody Lumia 920 replaces the one with the interchangeable covers. Also different thickness, in the case of conditional Lumia 920 from the integration of a camera module particularly complex and the weight of the two smartphones (185 grams for the Lumia 920 and 160 grams for the Lumia 820).
The Nokia Lumia 820, until now, seemed a bit eclipsed by his older brother the Lumia 920, but for some users, however, lower weight and thickness with lower price tag and features like interchangeable covers and removable battery with expandable memory via microSD could make a difference.